?
Need assistance?
Ask your
local 13 dealer
32
Tyre pressure is given either as maximum
pressure or as a pressure range. How a tyre
performs under different terrain or weather
conditions depends largely on tyre pressure.
Inflating the tyre to near its maximum
recommended pressure gives the lowest rolling
resistance; but also produces the harshest ride.
High pressures work best on smooth, dry
pavement. Very low pressures, at the bottom of
the recommended pressure range, give the best
performance on smooth, slick terrain such as
hard-packed clay, and on deep, loose surfaces
such as deep, dry sand. Tyre pressure that is too
low for your weight and the riding conditions can
cause a puncture of the tube by allowing the tyre
to deform sufficiently to pinch the inner tube
between the rim and the riding surface. Ask your
local 13 dealer
to recommend the best
tyre
pressure for the kind of riding you will most
often
do. Inflate your tyres to that pressure, using
a
pressure gauge. Then, check inflation as
described in Section 1.C so you’ll know how
correctly inflated tyres should look and feel when
you don’t have access to a gauge. Some tyres
may need to be brought up to pressure every
week or two.
Some special high-performance tyres have
unidirectional treads: their tread pattern is
designed to work better in one direction than in
the other. The sidewall marking of a
unidirectional tyre will have an arrow showing the
correct rotation direction. If your bike has
unidirectional tyres, make sure that they are
mounted to rotate in the correct direction.
2 Tyre Valves
There are primarily two kinds of bicycle tube
valves: The Schraeder Valve and the Presta
Valve. The bicycle pump you use must have
the fitting appropriate to the valve stems on
your bicycle.
The Schraeder valve is like the valve on a car
tyre. To inflate a Schraeder valve tube, remove
the valve cap and clamp the pump fitting onto
the end of the valve stem. To let air out of a
Schraeder valve, depress the pin in the end of
the valve stem with the end of a key or other
appropriate object.
The Presta valve (fig. 21) has a narrower
diameter and is only found on bicycle tyres.
To inflate a Presta valve tube using a Presta
headed bicycle pump, remove the valve cap;
unscrew (anticlockwise) the valve stem lock nut;
and push down on the valve stem to free it up.
Then push the pump head on to the valve head,
and inflate.
To inflate a Presta valve with a Schraeder pump
fitting, you’ll need a Presta adapter (available at
your
local 13 dealer
) which screws on to
the
valve stem once you’ve freed up the valve.
The
adapter fits into the Schraeder pump fitting.
Close the valve after inflation. To let air out of a
Presta valve, open up the valve stem lock nut
and depress the valve stem.
WARNING: Patching a tube is an
emergency repair. If you do not apply
the patch correctly or apply several patches,
the tube can fail, resulting in possible tube
failure, which could cause you to lose control
and fall. Replace a patched tube as soon as
possible.
Fig. 21
turn locknut
Presta valve
13
owners manual GENERIC A5 aw
05/05/14
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